Yttrium complexes of the chelating, C2-symmetric, bis(silylamido)biphenyl ligand [DADMB]2-(={[6,6′-Me2- (C6H3)2] (2,2′-NSiMe2(t)Bu)2}2-)

The yttrium bis(silylamido)biphenyl complex [DADMB]YCl(THF)(2) (2; DADMB = 2,2'-bis((tert-butyldimethylsilyl)amido)-6,6'-dimethylbiphenyl) was prepared from Li-2[DADMB].2THF and YCl3(THF)(3), and its structure was determined by X-ray crystallography. Compound 2 reacts with MeLi and (Me3Si)(2)CHLi to give the corresponding alkyl derivatives [DADMB]YMe(THF)(2) (3) and [DADMB]Y[CH(SiMe3)(2)](THF)(OEt2) (5), respectively. In the presence of silicone grease, the reaction of 2 with MeLi produces the yttrium trimethylsiloxide complex [DADMB]Y(OSiMe3)(THF)(2) (4), which was also crystallographically characterized. Both 3 and 5 react with phenylsilane or H-2 to give the insoluble, dimeric yttrium hydride {[DADMB]Y(mu-H)(THF)}(2). C6H6 (6) The alkyl derivatives 3 and 5 exhibit only limited olefin polymerization activity; however, the hydride 6 reacts rapidly with ethylene or 1-hexene to give a single insertion product. The resulting yttrium ethyl complex 7 was structurally characterized. Compound 6 reacts with pyridine to produce a mixture of the isomeric 1,2- and 1,4-insertion products 9 and 10, [DADMB]Y(NC5H6)(pyr)(2). Compound 9 converts quantitatively to 10 upon heating.